I just replaced driver side ball joints and realized that my 4x4 is permanently engaged on that side b/c the retaining lock ring "ears" are too big and prevent the 4x4 from coming all the way out . . . looking on the passenger side I see that there is not any lock ring (I hope I have the proper name for this ring that snaps into the grove on the end of the axle shaft. It's the last thing to go on before the 3-screw cap goes back). Ford says this used to be part of a $75 repair kit and that there should be one on each side. Any ideas where I might find this part or a substitute part?

Thanks,
Pete